After this year’s long hot summer, winter’s back in our mountains again, burying the effects of that exceptional season. Our last article on the weather gave details of the summer temperatures of 2003 in the north of Italy; the results for some glaciers in the Alps are striking. Surveys performed in September revealed a very negative situation, with as much as 3 metres of ice being lost in the western Alps around an altitude of 3,000 metres. It should be remembered that under “normal†conditions at this altitude at the end of the summer there should still be some residual snow from the previous winter. This year’s extraordinary heat, even at high altitudes, not only evaporated all the snow still lying at heights of up to 3,300-3,500 metres, but also melted considerable quantities of ice hoarded from the snow of winters long past. During the hottest times of the summer, for example the first fortnight in August, at 3,000 metres up to 8 cm of ice were melting a day, the equivalent of 70,000 cubic metres of water per square kilometre of glacier. At least the melting of this reserve of ice, built up over many decades, did in some cases make it possible to keep up the level of irrigation of cultivated land and rice fields on the plains, even during the worst periods of the long summer drought. The Ciardoney glacier on the Piedmont side of the Gran Paradiso lost a total of 3 metres of water equivalent, one of the worst results since measurements began in 1992. It has been calculated that in the three months of summer 2003, from the beginning of June to the beginning of September, the ice melt removed around 3,200,000 m3 of water from the glacier. It was a hard year too for the Basodino glacier in Ticino Canton, near where it borders on the Italian valley of Val Formazza, with a net loss of 2 metres, according to measurements performed by Giovanni Kappenberger, a weather forecaster at the Observatory of Locarno-Monti. The autumn that followed showed a see-saw effect as regards the climate: October was a little cooler than usual, then November was again very warm for the season. The important fact was, however, that it finally began to rain abundantly, putting an end to the severe drought. In late October-early November there were some heavy snowfalls in the Alps even at low altitudes, an early appearance of the snow, to the extent that some places recorded their earliest-ever autumn snow. This was the case in the upper Susa Valley, where the quantity of snow that fell in October and November 2003 was the highest since 1920. At the moment the snow cover at 2,000-2,200 metres is as much as 150-200 cm deep in the western Alps, and it is continuing to lie quite deeply thanks to the winter cold which has finally arrived after weeks of unusually mild weather for the end of the autumn. The early snowfalls of October call to mind a local saying in the Turin area, “La fiòca sla fòja a dà nen nòja†(when it snows on trees that still have their leaves, i.e. early in the autumn, we won’t be troubled much by snow in the winter). This suggests that a dry winter should follow a snowy autumn. Should we be worried? Not necessarily – the data referring to snowfalls in the last century do not bear out the proverb, however attractive it might appear.
Further information on the situation of the glaciers and on the unusual climate of 2003 from www.nimbus.it
